Hot water tank

ABSTRACT

A hot beverage dispenser is provided with an improved tank for storing water and for maintaining the water at the proper hot temperature. The tank is formed in a pair of separable components including a metallic bottom section and a transparent upper plastic section. An internal heating element is disposed within the bottom section together with an adjacent thermostatic control. The bottom metal tank section is insulated.

United States Patent 91 Arzberger [111 3,730,144 [4 1 May 1, 1973 HOTWATER TANK [75] Inventor: William A. Arzberger, Medfield,

Mass.

[73] Assignee: Jet Spray Cooler, lnc., 'Waltham,

Mass.

[22] Filed: Feb. 17,1972

[2]] Appl. No.: 227,495

[52] US. Cl. ..122/13 A, 126/361, 220/82 R [51] Int. Cl ..F22b 5/00 [58]Field of Search ..l22/l3 A, 13 R, 14,

[56] References Cited UNITED STATES PATENTS 2,718,583 9/1955 Noland eta1. ..126/361 X 3,189,225 6/1965 Maxwell ..126/362 X 3,223,492 12/1965Geitz ..220/82 X 3,565,045 2/1971 Knox, Jr. ..l22/l 3 PrimaryExaminerl(enneth W. Sprague Att0rneyArthur Z. Bookstein [5 7] ABSTRACT Ahot beverage dispenser is provided with an improved tank for storingwater and for maintaining the water at the proper hot temperature. Thetank is formed in a pair of separable components including a metallicbottom section and a transparent upper plastic section. An internalheating element is disposed within the bottom section together with anadjacent thermostatic control. The bottom metal tank section isinsulated.

6 Claims, 1 Drawing Figure HOT WATER TANK BACKGROUND OF THE INVENTIONThis invention relates to improvements in water tank construction, andparticularly to hot water tanks of the type used in dispensers for hotliquids such as hot chocolate and the like. For example, the hot watertank may be employed in dispensing apparatus of the type shown in U.S.Pat. No. 3,568,887 to Jacobs et al.

Typical prior hot water tanks as used in beveraged dispensers have beenmade from a non-corroding metal such as stainless steel, brass, copperor from porcelain lined tanks. In addition to the relatively high costof material and manufacturing of such prior tanks, their use has notbeen free from difficulty. For example, all such tanks tend to developscale formations on their inner surface resulting from the impurities inthe water. Scale formation causes numerous problems which will bereadily apparent to those familiar with the art. In the prior water tankconstruction, it is extremely difficult to clean effectively the insideof the tank to remove the built up scale. Access to the interior of thetank generally is extremely poor. Additionally, there is no way toeasily and effectively inspect the interior of such prior tanks. As aresult, the hot water tanks often would not be cleaned at all and wouldbe used until the scale formation eventually caused failure of the tankto function properly, at which time the entire tank would be replaced,long before its possible use for life had expired.

The complete unitary metallic construction also tends to causedifficulties regarding the heating unit and control for operating theheating unit to maintain the water at the desired temperature. Priortanks have employed either an internal heater which is permanentlybrazed into the tank oran external heater wrapped about the metallictank to transmit heat to the water through the heat conductive tankwall. It was necessary to insulate fully the entire water tank with anappropriate surrounding insulative material. In those prior tanks whichemploy an internal heater, access to the heater element itself isrelatively poor for the same reasons as is access to the inner surfaceof the tank for cleaning purposes. With the external heaters, theinsulation required is considerably increased. In instances where thetanks may inadvertently empty itself, the response by the thermostaticcontrol necessarily lags the temperature of the heater element.Repetitive dry" operation of the heater element accellerates itsoxidation and results in premature failure. It is among primary objectsof the invention to provide an improved tank construction which avoidsthe foregoing difficultIeS.

SUMMARY OF THE INVENTION In brief, my improved hot water tank isfabricated from a pair of separable sections including an upper plasticsection and a lower metallic section. The upper plastic section isconsiderably longer than the lower metallic section so that the greaterproportion of the tank is of the plastic construction. The top andbottom sections are detachably connectable so that the inner surfaces ofboth may be exposed fully for easy cleaning. Additionally, the upperplastic section preferably is transparent to permit inspection of thecondition of the interior of the tank without disassembling any of thetank elements.

The tank includes an internal heater element mounted to and within thelower metallic section and a bimetallic thermostatic control is alsomounted to the lower metallic section by means of a mount which extendsinto the tank, so that its bimetallic element is located in heattransfer .proximity to the heater element. The heater and thermostaticcontrol mount are disposed within the bottom section so that when thetank is disassembled the heater is readily exposed and easilyaccessible.

The tank also includes a specially formed seal between the matingplastic and metallic sections which also permits the different rates ofexpansion of the metal and plastic without disrupting the seal.

Among the objects of the invention is to provide an improvedconstruction for a hot water tank for a hot beverage dispenser.

Another object of the invention is to provide a hot water tank in whichthe condition of the interior may be inspected readily and easily.

A further object of the invention is to provide a hot water tank whichmay be disassembled and cleaned easily.

Another object of the invention is to provide a hot water tank, aheating element and thermostatic control element which are arranged sothat the thermostatic control may shut off the heater element promptlyin the event that the tank runs dry.

Another object of the invention is to provide a hot water tank whichrequires relatively little supplemental insulation.

Still another object of the invention is to provide a hot water tankwhich is inexpensive to manufacture.

DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT Theinvention is illustrated as used in a hot beverage dispenser of the typeshown in the aforementioned U.S.

patent. As described more fully in that patent, the dispenserarrangement includes a housing 10,

discharge nozzle 12 and a hood 14 which houses an arrangement fordispensing the beverage mix, such as hot chocolate, into a mixing device16. Mounted rearwardly within the housing on a base 18 and appropriatebracket 20 is the hot water storage tank 22.

As'described more fully below, the tank 22 is formed in two sections, anupper plastic section 24 and a lower metal section 26. Water is admittedinto the tank through the lower section 26 by the fitting 28. The wateris supplied to the machine through an inlet fitting 30 which directs thewater to a needle valve flow control 32 through appropriate tubing andthen from the flow control valve 32 through tubing 34 to the fitting 28.Valve means are located along this flow path to control operation of thedevice as described more fully in the aforementioned patent. The fitting28 also includes a drain tube 36 to enable the entire tank to be drainedif desired.

The upper end of the tank includes an outlet fitting which directs theheated water through the tubing 40 into the mixing device 16. The hotwater is fed through the tube 40 as fresh water is introduced, in ameasured volume, into the inlet of the tank through the fitting 28.

As described above, the upper section 24 of the tank is formed from anappropriate plastic suitable for use with hot water having a temperaturenormally approximating 180F. The upper tank section 24 defines thesubstantially greater portion of the tank with the lower metallicsection 26 defining a relatively small portion of the total tank volume.The upper tank section 24 preferably is transparent to enable theinterior of the entire tank to be inspected without disassembling thetank. The upper tank section may be fabricated according to well knowninjection molding techniques to include a neck 42 at its upper end forfastening to the outlet fitting 38. The lower. end of the upper tanksection 24 is formed to define an outwardly extending circumferentialflange 44. A circumferential groove is formed in the underside of theflange 44 to receive an O-ring seal 46 as described below.

The bottom section 26 of the tank is formed from a corrosion resistantmetal such as stainless steel. The bottom section 26 is formed with anoutwardly extending circumferential flange 48 which is adapted to mateabuttingly with the flange 44 on the upper tank section 24. The outerend of the flange 48 may be downturned as shown. The flanges are securedtogether by circumferentially spaced bolts 50. Preferably, a metalbacking ring 52 surrounds the upper tank section 24 against the flange44 to distribute the clamping force of thebolts 50 fully about theplastic flange 44. The O-ring 46 is disposed so that it bears firmlyagainst the upwardly facing surface of the flange 48 of the lower tanksection 26. From the foregoing it will be apparent that the interior ofthe tank may be inspected without disassembling any of the tank parts.If access to the interior of the tank is desired, as for cleaning scaledeposits, the tank sections may" be separated easily to expose the innersurfaces of the tank sections 24, 26 through the enlarged openings attheir mating ends.

In the illustrative embodiment, the tank includes the electricresistanceheater 54 mounted within the lower section 26. The heater 54may be supported firmly in the lower section 26 by brazing it at thejuncture of the heating element and the wall of the lower section 26. Inthe preferred embodiment, the heater 54 is contained, in its entirety,within the lower metallic section and does not extend into the plasticupper section 24 of the tank. This minimizes likelihood of excessiveheat from the heater damaging the plastic upper section 24 in the eventof heater malfunction.

In order to further reduce likelihood of damage to the heater 54 or anyof the other elements of the tank in the event that the tankinadvertently runs dry with the heater continuing to operate, abimetallic thermostat 56 is mounted to the lower tank section 26. Thebimetallic thermostat 56 is mounted to the tank by a mount 58 secured tothe tank. The mount 58 has a portion disposed interiorally of the tankin proximity to the heater 54 to receive heat and conduct heat to thebimetallic thermostatic element 56. The element 56 is in heat conductiverelation to the mount 58. Heat is received by bimetallic thermostat bothfrom the walls of tank section 26 and from the mount 58. The thermostat56 may be selected from any of a number of commercially availabledevices in which the temperature sensitive bimetallic element may bemounted as described above. In the event that the tank did run dry,inadvertently, the excess heat developed by the heating coil 54 would besensed in a relatively short time by the mount stem 58 so that thethermostatic control 56 may shut off the power to the coil 54. Theheater 54 and bimetal thermostatic control device 56 preferably shouldbe selected so that the heater 54 is shut off in no more thanapproximately 2 minutes of dry operation.

In order to insulate the tank and the hot water contained therein, onlythe lower section 26 need be provided with external, supplementalinsulation. As shown in the drawing, an appropriate wall arrangement 60formed from any of a number of readily available insulative materialssurrounds'the sidewall and bottom of the lower section 26. The uppertank section 24 is self insulative by reason of its plasticconstruction. For this purpose, the plastic material from which theupper section 24 is fabricated also should have satisfactory heattransfer characteristics. Selection of an appropriate plastic materialis considered to be a matter of choice and the techniques for properselection will be readily apparent to those skilled in the art. I

It should be understood that the foregoing description of the inventionis intended merely to be illustrative thereof and that other embodimentsand modifications may be apparent to those skilled in the art withoutdeparting from its spirit. Y

Having thus described the invention what I desire to claim and secure byLetters Patent is:

1. A hot water tank comprising:

an upper plastic tank section having an outlet formed at its upper end;

a lower metal tank section having an inlet formed a its lower end; meansfor detachably connecting said lower end of said upper tank section tosaid upper end of said lower tank section to define said complete tankvolume, said upper tank section being larger than said lower tanksection and defining a larger proportion of total tank volume; v Isealing means for sealing said connected ends of said upper and lowertank sections; and 1 heat transfer means disposed within said lower tanksection. I I H 2. A water tank as defined in claim 1 wherein said heattransfer means comprises heating means.

3. A water tank as defined in claim 1 wherein said upper tank section isformed from a transparent plastic thereby to enable the interior of saidtank to be inspected without disassembly thereof.

4. A water tank as defined in claim 2 further comprising:

means encasing said lower section of said tank within an insulativeshell. v

5. A water tank as defined in claim 1 further comprising:

temperature sensing means mounted to said lower tank section, so thatthe responsive sensing element thereof is disposed in heat conductingproximity to said heat transfer means thereby to control operation ofsaid heat transfer means within a minimum'time after said heat transfermeans has begun operation beyond predetermined limits.

6. A water tank as defined in claim 1 wherein said means for supportinga sealing O-ring between said means connecting said upper and lower tanksections to each other comprises:

the mating ends of each of said upper and lower tank sections having anoutwardly extending circum- 5 ferential collar formed integrallytherewith;

collars when said tank sections are brought together at said collars;and means for securing said flanges together.

1. A hot water tank comprising: an upper plastic tank section having anoutlet formed at its upper end; a lower metal tank section having aninlet formed at its lower end; means for detachably connecting saidlower end of said upper tank section to said upper end of said lowertank section to define said complete tank volume, said upper tanksection being larger than said lower tank section and defining a largerproportion of total tank volume; sealing means for sealing saidconnected ends of said upper and lower tank sections; and heat transfermeans disposed within said lower tank section.
 2. A water tank asdefined in claim 1 wherein said heat transfer means comprises heatingmeans.
 3. A water tank as defined in claim 1 wherein said upper tanksection is formed from a transparent plastic thereby to enable theinterior of said tank to be inspected without disassembly thereof.
 4. Awater tank as defined in claim 2 further comprising: means encasing saidlower section of said tank within an insulative shell.
 5. A water tankas defined in claim 1 further comprising: temperature sensing meansmounted to said lower tank section, so that the responsive sensingelement thereof is disposed in heat conducting proximity to said heattransfer means thereby to control operation of said heat transfer meanswithin a minimum time after said heat transfer means has begun operationbeyond predetermined limits.
 6. A water tank as defined in claim 1wherein said means connecting said upper and lower tank sections to eachother comprises: the mating ends of each of said upper and lower tanksections having an outwardly extending circumferential collar formedintegrally therewith; means for supporting a sealing O-ring between saidcollars when said tank sections are brought together at said collars;and means for securing said flanges together.